Release mechanism for ordnance apparatus and the like



RELEASE MECHANISM FOR ORDNANCE APPARATUS AND THE LIKE Filed Jan. 16, 1957 L. L. ANDERSON ET AL July 18, 1961 2 Sheets-Sheet 1 RELEASE MECHANISM FOR ORDNANCE APPARATUS AND THE LIKE Filed Jan. 16, 1957 July 18, 1961 1.. L. ANDERSON ETAL 2 Sheets-Sheet 2 M MEWW United States Patent 2,992,594 RELEASE NIECHANISM FOR ORDNANCE APPARATUS AND THE LIKE Lloyd L. Anderson, Grand Rapids, James 0. Rap, Grandville, and Donald L. McCurdy, GrandRapids, Mich., assignors to Jervis Corporation, Grandville, Mich., a corporation of Michigan Filed Jan. 16, 1957, Ser. No. 634,476 7 Claims. (Cl. 89-15) This invention relates to an improved release mechanism and more particularly to a mechanism adapted to release or enable the release of a retained element selectively in response to the control of an operator.

It is a principal object of this invention to provide improved apparatus for selectively controlling the retention or release of a loop or ring of wire or the like.

In the utilization of ordnance stores such as .bombs and rockets it is highly desirable to provide means by which the store may be rendered completely safe and not subject to accidental ignition. This is generally accomplished by providing an arming device which orients the parts of the fuse and the explosive portion of the missile only at a time determined by the requirements of the situation, preferably immediately prior to the release of the missile during an attack. If the missile is armed substantially prior to the utilization thereof, a substantial danger exists that the missile will be accidentally fired or ignited through excess shock or the effects of a counter attack. This is extremely hazardous to the personnel handling the ordnance apparatus and the operators of aircraft or other missile bearing vehicles. Use of permanently armed missiles would also greatly complicate the care required in handling and storing explosive missiles.

It is therefore desirable to employ a device which selectively controls the arming of explosive missiles so that, for example, bombs carried beneath an aircraft may have an arming Wire extended therefrom which is retained in fixed relationship to the aircraft. Thereby, upon release of the missile, the arming wire is withdrawn from the missile placing the various parts thereof in condition for firing at the critical time or under the critical conditions of impactor proximity.

Furthermore it is desirable that such arming apparatus be capable of remote control by a pilot or the like to selectively release the arming wire, permitting the discharge of the missile in an emergency without conditioning the various parts thereof for firing. For example, it is sometimes desirable or necessary to discharge missiles while over friendly territory or a portion of an airfield. Or in the alternative, it may be desired to selectively release the arming wire, irrespective of the condition or the position of the missile, either at a time following release of the missile or while the missile is retained in place.

It is an object of this invention to provide an arming release mechanism for installation in a vehicle which is easy to utilize in the loading, dropping, and unloading of missiles from the vehicle. 7

It is another object of this invention to provide an improved arming release. mechanism which may be selectively actuated to permit the discharge of a missile with or without prior arming or setting of the fuse thereof in accordance with the desires of an operator.

It is a further object of this invention to provide an improved arming release mechanism which may be selectively actuated from a remote position.

It is still another object of this invention to provide an improved arming reelase mechanism in which an associated arming wire may be resiliently maintained in the arming position with a force less than that required to arm the missile.

It is still another object of this invention to provide an improved arming release mechanism capable of selective remote actuation for discharging the arming wire following dispatch of the armed missile. I

It is still another object of this invention to provide an improved release mechanism which is rugged and capable of operation under adverse mechanical and cli= matic conditions.

It is still another object of this invention to provide an improved arming device including a solenoid for actuating an aiming device wherein the immovable portions thereof are sealed while the sealing material is isolated from the movable elements.

It is a further object of this invention to provide anv improved arming device having two pivotally mounted arming legs, independent movement of either one being suflicient to release the retained element.

Further and additional objects of this invention will become manifest from a consideration of this description, the accompanying drawings, and the appended claims.

In one form of this invention an improved release mechanism is provided including a mounting, a pair of pivotally mounted generally parallel retaining arms and a solenoid carrying an interference or latching means capable of selectively blocking the arms to prevent pivotal movement thereof. More particularly, the arms are pivotally mounted in generally parallel relationship and adapted for vertical mounting with the lower portions thereof slightly separated and the upper portions urged apart by a coil spring compressed therebetween. The lower portions retain an arming wire as discussed heretofore with a resilient force such that deployment of the missile will cause the arming wire to fall away from the resiliently abutting lower arms without arming the missile. A latching plug is slidably mounted above the upper portion of the arms and normally urged by associated spring means to a position in spaced noninterfering relationship with the arms. A solenoid is provided for shifting the latching plug downwardly into an interfering position whereby the arms are locked with the lower portions thereof together. When thus locked, deployment of the associated missile will cause removal of the arming wire therefrom and consequent preparation of the missile for detonation in the conventional manner.

In an alternate embodiment of this invention a solenoid assembly is provided having a second winding portion adapted to shift the latching means to a third position wherein shaped outer surfaces of the upper arm portion are engaged and urged inwardly to open or spread the lower arm portions, thus releasing the arming wire normally retained therebetween, irrespective of the condition or position of the missile or the force being applied to the wire.

For a more complete understanding of this invention reference will now be made to the accompanying drawings wherein:

FIG. 1 is a longitudinal sectional view of one embodiment of this invention incorporating a single action solenoid;

FIG. 2 is an elevational view of the embodiment of FIG. 1, partially in section, showing the solenoid in the actuated position;

FIG. 3 is a longitudinal sectional view of an alternate embodiment of the invention illustrating the solenoid armature and latching means in a second actuated position;

FIG. 4 is a bottom plan view of the embodiments of FIGS. 1 and 3;

FIG. is a fragmentary perspective illustration of the solenoid utilized in the embodiment of FIG. 1;

FIG. 6 is a perspective illustration of the latching means including cam surfaces and interfering means which may be utilizied in the embodiment of FIGS. 1 and 3; and

FIG. 7 is a diagrammatic exploded view of the elements utilized in constructing the dual-acting solenoid forming a part of the embodiment of FIG. 3.

Referring now to the drawings and more particularly to 'FIG. 1, an arming device for accomplishing the objects set forth above is illustrated and includes a solenoid actuating mechanism 10 and arming unit 12. While the actuating mechanism 10 and arming unit 12 cooperate in a unique maner it will be clear from the description that follows that the arming unit 12 is a versatile device capable of operation in association with other actuating mechanisms and, conversely, certain novel features of the actuating solenoids described herein makes said solenoids applicable to other uses which will appear to one skilled in the art.

The actuating unit 12 is assembled within a cylindrical support 14 having a mounting flange 16 formed at one end thereof' The mounting flange 16 is provided with apertures 18 which are adapted to receive appropriate mounting bolts preferably engaging a structural portion of the aircraft in such a manner that the arming device is maintained in a generally vertical position, as illustrated in FIG. 1. between opposite walls of the cylindrical support 14 and retain arms 24 and 26, respectively, freely rotatable thereon. The lower ends 28 and 30 of arms 24 and 26 are flared outwardly somewhat and have aligned apertures therein which receive supporting studs 32 and 34. The studs 32 and 34 have flat adjacent faces 36 and are of a hardened material resistant to wear and capable of withstanding substantial stresses. The arms 28 and 30, on the contrary, may be constructed of a soft light weight A pair of transverse pins 20 and 22 extend 's g x 4 The seal 50 is retained in position by a threaded insert 60 which urges a resilient normally flat washer 62 against the seal 50 in such a manner that the washer 62 is distorted to a frusto-conical shape as illustrated in FIG. 1. Thus, the seal 50 is normally maintained under yieldable compression to insure a continuous and positive seal. Recesses 61 are provided in insert 60 whereby a tool may engage the recesses to facilitate the insertion and removal of the insert 60.

A latch or interference means 64, as illustrated more clearly in FIG. 6, is supported within the cylindrical support 14 by an axially slidable shaft 66. Latching means 64 is secured to shaft 66 by a transverse pin 68 passing through aligned apertures in the two elements. It is preferred that pin 68 be closely fitted to the apertures in the associated elements whereby they are frictionally held in integral assembly. Preferably the pin is completely contained within the latching means 64 whereby the pin cannot interfere with normal operation thereof.

The latching means 64 includes an apertured central stud 70 and a pair of substantially parallel cam surfaces 72 and 74. Surfaces 72 and 74 are connected by cross bars 76 and 78 to form a generally rectangular assembly, and stud 70 isintegrally connected to cross bars 76 and 78 by supporting webs 80 and 82. The shaft 66 is slidable in a cover and core element 84 which encloses the cylindrical support 14 and also provides a central core 92 for solenoid 10. Cover'84has a downwardly extending threaded flange 86 which threadedly engages a correspondingly threaded upper portion of support 14. The upper shaped ends 42 and 44 of arms 24 and 26 normally abut against the innersurface of threaded flange 86 when the studs 32 and 34 are contiguous. An armature material such a aluminum whereby the over-all weight 1" of the arming unit is greatly reduced.

The arming wire 38 is partially illustrated in FIGS. 1, 2 and 3, and it will be understood that this wire is a closed loop, one end of which extends downwardly into a supported missile in such a manner that withdrawal of the loop and wire from the missile will condition and arm the missile so that upon the occurrence of other predetermined conditions such as proximity, impact, or the passage of time the missile will be detonated. The

studs 32 and 34 are normally maintained in resilient contiguity by a coil spring 40 which is compressed between the upper arm portions 42 and 44 of arms 24 and 26, the coil spring being seated in appropriate recesses 46 and 48 in the'upper arm portions. The spring 40 is constructed ofa material and size such that the arming wire 38 may be withdrawn from the position illustrated in FIG. 1 between studs 32 and 34 by a force less than that necessary to withdraw the arming wire 38 from the missile. Thus, when the arming device is in the condition illustrated in FIG. 1 deployment of the missile will permit the missile and arming wire to fall as a unit without conditioning the missile for detonation.

A flexible seal 50 is provided to protect the moving parts of the arming unit from atmospheric conditionsand contamination. The seal 50 has an annular flange 52 which is received in a recess formed in cylindrical support '14 and has two spaced central apertures which receive arms 24 and 26. The seal 50 is normally a substantially flat planar apertured disc having flange 52 formed thereabout. However, in placing the seal in its operative position in support 14 the seal is distorted as illustrated in the sectional view of FIG. 1.

The inner web 54 is folded upon itself and engages small lip portions 56 extending inwardly from the legs 24 and 26. The outer edges 58 of the seal '50 engage and lie against the shaped lower portions of legs 24 andv 26.

88 is secured at the upper end of shaft 66 and a coil spring havingsubstantial resiliency is normally compressed within a central annular recess in core portion 92 between the lower surface of armature 88 and the bottom annular surface of the annular cavity in core 92.

Thus, as can be seen from FIG. 1, spring 90 urges latching means 64 upwardly whereby cam surfaces 72 and 74 engage correspondingly shaped surfaces on the upper arms 42 and 44. However, the coeflicieint of spring 90 is so related to the compression coefficient of spring 40 that the upward force on shaft 66 is insufficient to compress spring 40 and consequently the engagement of cam surfaces 72 and 74 with upper arms 42 and 44 will not produce inward movement of those arms. In fact, in the embodiment illustrated in FIG. 1 employing a single action solenoid, the cam surfaces 72 and 74 may be omitted and the latching means comprise simply a stud 70 in which event the stud will rest with its upper edge 71 abutting cover 84.

Upon energization of solenoid 10, armature 88 will be attracted to core 92 compressing spring 90 and positioning plug 70 as illustrated in FIG. 2. When so positioned, as will be clear from FIG. 2, the application of a downward force to arming wire 38 will not effect spreading of studs 32 and 34 as the stud 70* is disposed between the adjacent faces 94 and 96 whereby inward movement of the upper arms 42 and 44 is prevented. Thus, the arming wire 38 'will be withdrawn from the falling missile conditioning the missile for detonation.

Referring once again to FIG. 1, the solenoid assembly 10 will be described in greater detail. An outer protective sleeve 98 is positioned on cover 84 and secured thereto by appropriate means such as brazing compound 100 whereby sleeve 98 encloses the upper end of support 14. A sealing ring 102 is compressed between shaped adjacent faces of cover 84 and support 14 whereby the chamber defined by support 14 is completely sealed against contamination.

A cylinder 104 extends upwardly from cover 84 and receives therein a solenoid winding 106. Winding 106 is formed on a bobbin 108 having "end bells 110 and 112.

.scribed in detail.

This Wound winding is, in the course of assembly of the unit, placed over core 92 and positioned as illustrated in FIG. 1. An annular shoulder 114 is formed on core 92 and has an outer diameter slightly greater than the internal diameter of bobbin 108. As bobbin 108 is preferably formed of a deformable insulating material such as nylon, annular shoulder 114 will be embedded into the bobbin, forming a seal between the bobbin and core 92.

A cover assembly for solenoid is provided and this cover assembly includes a centrally apertured insulating plate 116 having diametrically opposed apertures therein through which pass axial extensions 118 of bobbin 108. Below plate 116, a magnetic end bell 117 including a downwardly extending cylindrical core portion 130 is disposed. Disposed above the end plate 116 is a centrally 'apertured insulating disc 120 having terminal posts 122 and 124 secured thereto. Insulating disc 120 and plate 116 are secured together by a central rivet 126 which also supports a downwardly extending cup-shaped closure 128. Closure 128 has a'slightly conical configuration whereby it rigidly engages the downwardly extending cylindrical portion 130. Downwardly extending cylindrical portion 130 has an outwardly extending annular shoulder 132 identical to the shoulder 114 described above, and this shoulder :132 engages yieldable bobbin 108 in sealing engagement.

Flexible conductors 134 and 136 extend upwardly from the solenoid winding 106 through axial extensions 118 and are secured to terminals 122 and 124. Supplementary conductors 135 and 137 are secured to the terminals and extend upwardly for connection to other extrinsic controls. The entire solenoid assembly is, in the last step of production, completely encased in a sealing or potting compound such as a casting resin or the like. This potting compound 125 completely surrounds the coil 106 and the end assembly including cover 116 and insulating disc 120, but is prevented from entering the area surrounding armature 88 by the annular interference shoulders 114 and 132 and the flared cup 128. Thus, a compact, completely sealed reliable unit is provided capable of selectively controlling the retention of an arming wire between a pair of supporting studs.

In the alternate embodiment illustrated in FIG. 3, an arming unit 12 identical to that described above is employed. The arming unit includes the cylindrical support 14-containing pivotally mounted arms 24 and 26 adapted to resiliently retain an arming wire 38 as already de- However, in this embodiment a double acting solenoid unit 138 is provided which is capable of performing the functions already described with regard to the embodiment of FIG. 1, but is further capable of selectively and positively releasing arming wire 38 without the application of any substantial withdrawal force thereto. This selective release of arming wire 38 is accomplished by the engagement of cam surfaces 72 and 74 with the corresponding shaped outer surfaces of upper arms 42 and 44. Solenoid unit 138 is adapted to raise latching means 64 upwardly to position arms 24 and 26 as illustrated .in FIG. 3.

Solenoid unit 138 includes an armature 1'40 slidably mounted for movement within a central aperture in an upper winding 142 and a lower winding 152. When the armature 146 of solenoid 138 is drawn upwardly by the energization of upper winding 142, cam surfaces 72' and 74 are drawn upwardly to force upper arms 4-2 and 44 together to spread studs 32 and 34 and thus release arming wire 38. As described with regard to the embodiment of FIG. 1, a light coil spring 144 is compressed between a core portion 146 of a cover 148 and the lower surface of armature 140. Coil spring 144 surrounds a pin 150 which is secured to latching means 64 and to armature 140. The second winding 152 is disposed within the solenoid unit 138 below the position normally assumed by armature 140. Thus, energization of lower winding 152 will draw armature 140 downwardly to a position generally corresponding to the position illustrated in FIG. 2 whereby stud 70 of latching means 64 will be disposed between the upper arms 42 and 44, preventing spreading of studs 32 and 34, and consequently preventing the withdrawal of arming wire 38.

The embodiment of FIG. 3 is illustrated with the upper solenoid winding 142 energized whereby the armature 148 is in its uppermost position and thus the studs 32 and 34 are separated. It will be understood that when the winding 142 is de-energized the force of spring 40 tendingto spread upper arms 42 and 44 will be suflicient to overcome the force of spring 144 and thus centrally position the armature 148 with the studs 32 and 34 in resilient abutment. Upon subsequent energization of the lower solenoid winding 152, the armature 140, and latching means 64 will move downwardly to lock the arms 24 and 26 as illustrated in FIG. 2.

The construction of dual solenoid 138 is similar to that described with regard to solenoid 10. The housing 154 extends upwardly from cylindrical support 14 and encases the entire solenoid unit. Cover 148 has a lower threaded flange which engages support 14, an upwardly extending core 146 having a central recess to receive spring 144, and an outwardly extending lip 149 which supports housing 158. An insulated bobbin 156 supports winding 152 and the bobbin and winding are disposed about core 146. The lower end bell 157 has a radial slot 159 formed therein and the upper end bell 158 of bobbin 156 is provided with passageways 168 and 162, the slot and passageways being provided to receive the connecting conductors for winding=152. This assembly is best illustrated in the exploded view of FIG. 7.

Disposed above upper end bell 158 is a spacer 164 preferably composed of a soft iron material. Spacer 164 is provided with axial recesses to receive the channels 168 and 162 which pass the terminal conductor portions of winding 152 upwardly. Disposed above and partially within soft iron spacer 164 is a brass insert and guide 166. Brass guide 166 insures alignment and accurate movement of armature 140. Supported around brass insert 166 is a second bobbin 168 carrying upper winding 142. The lower end bell 170 of bobbin 168 is provided with recesses to receive the channels 160 and 162 and the upper end bell 172 is provided with similar channels 174, 176 and 178 which communicate with the upper open end of the solenoid unit 138. One winding terminal wire of the upper winding 142 lies in radial slot 171 of end bell 17 8 and is connected to a corresponding winding terminal wire of lower winding 152. The terminal wire of lower winding 152 passes through radial slot 159, and passageway 162, above which the upper terminal is connected thereto. These wires pass through passageway 176 and are permanently secured to a terminal post 180' mounted in an aperture 181 in an insulating support 182 and resting on the lower insulating support 184. Similarly, the other end of lower winding 152 extends upwardly through channels 168 and 174 and is connected to a second terminal post 186 which is also secured in insulating disc 182 and supporting disc 184. The other wire of upper winding 142 extends upwardly through channel 178 to a third terminal post not visible in FIG. 3 which is equally spaced from posts 180 and 186 and secured in disc 182 in an identical manner.

A soft iron end core 188 is disposed above upper winding 142 and rests on end bell 172. Thus, two magnetic circuits may be provided within the solenoid 138, the first providing a flux path for lower winding 152 includes core 146, armature 140, soft iron spacer 164, housing 154 which is also preferably of soft iron or magnetic steel, and cover 148. The upper winding 142 has a flux path provided which includes soft iron spacer 164, armature 140, upper core 188 and housing 154. Thus optimum efiiciency and a minimum size and weight are provided in an arming unit capable of selectively resiliently retain- 7 ing, positively retaining, or positively releasing an arming wire.

While two specific solenoid units are provided, each capable of cooperating in a unique manner with one particular arming unit, it will be apparent that the solenoid units or arming unit may be altered in various manners while still retaining the novel features and important advantages which are inherent in the structures described in detail herein.

Without further elaboration, the foregoing will so fully explain the character of our invention that others may, by applying current knowledge, readily adapt the same for use imder varying conditions of service, while retaining certain features which may properly be said to constitute the essential items of novelty involved, which items are intended to be defined and secured to us by the following claims.

We claim:

1. A release mechanism comprising Support means, two substantially parallel pins defining axes and mounted in spaced relationship in said support means, a retaining arm pivotally mounted on each of said axes, said arms substantially coextending in generally parallel relationship and each having cam shaped upper free end means and a retaining stud at the lower end, spring means urging said upper free ends apart whereby said studs are contiguous, and a latching means mounted on said support and selectively movable from a normal position free of said arms to a first position engaging the cam shaped upper free end means and urging said end means of said arms together against said spring to separate said studs to a release position and a second armed position whereby a portion of said latching means is disposed in a blocking position between said upper arms and maintaining said studs in the locked contiguous positions.

2. A release mechanism comprising a cylindrical support, two substantially parallel pins defining axes and mounted in spaced relationship transversely within said cylindrical support, a retaining arm pivotally mounted on each of said axes, said arms substantially coextending in generally parallel relationship and each having cam shaped upper free end means and a retaining stud at the lower end, spring means urging said upper free ends apart whereby said studs are contiguous, a latching means selectively movable from a normal position free of said arms to an upper position engaging said cam shaped end means and urging said ends together against said spring to separate said studs and an armed position whereby a portion of said latching means is disposed between said upper arms maintaining said studs in locked position, resilient means continuously urging said latching means to the normal position, actuatable means for urging said latching means to the upper position, and actuatable means for urging said latching means to the armed position.

3. A release mechanism comprising a cylindrical support, two substantially parallel pins defining axes and mounted in spaced relationship transversely within said cylindrical support, a retaining arm pivotally mounted on each of said axes, said arms substantially coextending in generally parallel relationship and each having cam shaped upper free end means and a retaining stud at the lower end, spring means urging said upper free ends apart whereby said studs are contiguous, a latching means selectively movable from a normal position free of said arms to an upper position engaging said cam shaped end means and urging said ends together against said spring to separate said studs and an armed position whereby a portion of said latching means is disposed between said upper arms maintaining said studs in locked position, spring means urging said latching means to said normal position, and solenoid means mounted above said cylindrical support and including a solenoid armature coaxially mounted and movable with said latching means and two coils surrounding saidarmature, the lower of said coils adapted to urge said armature downwardly, and the upper of said coils adapted to urge said armature upwardly, whenever said coils are selectively and alternately energized.

4. A' release mechanism comprising a cylindrical support, two substantially parallel pins defining axes and mounted in spaced relationship transversely within said cylindrical support, a retaining arm pivotally mounted on each of said axes, said arms substantially coextending in generally parallel relationship and each having a shaped upper free end and a retaining stud at the lower end, a spring urging said upper free ends apart whereby said studs are contiguous, said upper free ends having intermediate portions of substantially reduced diameter and upper, flared portions of increased outer diameter and defining a central cavity, and latching means comprising a central plug normally disposed above said central cavity and axially and transversely spaced cam surfaces extending generally parallel to said axes and normally disposed adjacent said reduced intermediate portions, said latching means being selectively movable from the normal position to an upper position wherein said cam surfaces engage said flared portions urging said studs apart against said spring and a lower armed position wherein said plug is disposed in said cavity maintaining said studs in locked position.

5. A release mechanism comprising a cylindrical support, two substantially parallel pins defining axes and mounted in spaced relationship transversely within said cylindrical support, a retaining arm pivotally mounted on each of said axes, said arms substantially coextending in generally parallel relationship and each having a shaped upper free end and a retaining stud at the lower end, a spring urging said upper free ends apart whereby said studs are contiguous, said upper free ends having intermediate portions of substantially reduced diameter and upper flared portions of increased outer diameter and defining a central cavity, latching means comprising a central plug normally disposed above said central cavity and axially and transversely spaced cam surfaces extending generally parallel to said axes and normally disposed adjacent said reduced intermediate portions, said latching means being selectively movable from the normal position to an upper position wherein said cam surfaces engage said flared portions urging said studs apart against said spring and a lower armed position wherein said plug is disposed in said cavity maintaining said studs in locked position, means urging said latching means to the normal position, actuatable means for urging said latching means to the upper position, and actuatable means for urging said latching means to the lower armed position.

6. A release mechanism comprising a cylindrical support, two substantially parallel pins defining axes and mounted in spaced relationship transversely within said cylindrical support, a retaining arm pivotally mounted on each of said axes, said arms substantially coextending in generally parallel relationship and each having a shaped upper free end and a retaining stud at the lower end, a spring urging said upper free ends apart whereby said studs are contiguous, said upper 'free ends having intermediate portions of substantially reduced diameter and upper flared portions of increased outer diameter and defining a central cavity, latching means comprising a central plug normally disposed above said central cavity and axially and transversely spaced cam surfaces extending generally parallel to said axes and normally disposed adjacent said reduced intermediate portions, said latching means being selectively movable from the normal position to an upper position wherein said cam surfaces engage said flared portions urging said studs apart against said spring and a lower armed position wherein said plug is disposed in said cavity maintaining said studs in locked position, spring means urging said latching means to said normal position, and solenoid means mounted above said cylindrical support and including a solenoid armature coaxially mounted and movable with said latching means and two coils surrounding said armature, the lower of said coils adapted to urge said armature downwardly, and the upper of said coils adapted to urge said armature upwardly, Whenever said coils are selectively and alternately energized.

7. A release mechanism comprising: a support housing; a solenoid mounted above said support housing and coaxial therewith including a core, electrical windings thereabout together defining a longitudinal and axial aperture therethrough, an armature movable coaxially in said aperture, a case about said core, an end cap closing said aperture at one end, and a sealing compound closing said case against atmospheric intrusion and closing on said cap; a pair of parallel spaced apart pins defining axes transverse of said support housing; a pair of retaining arms in opposed planar parallel register, one with the other, said 'arms each having an upper shaped free end and a lower depending portion each lower portion including a stud substantially in contacting register each with the other; spring means intermediate said arms and urging said lower depending portions of said arms into substantial contact at said studs; a resilient seal about said depending portions of said arms and in closing contact with said support housing; a shaft extending from said armature and movable therewith; a latch piece secured to said shaft and movable therewith selectively engageable and disengageable with said upper shaped free ends of said arms, thereby selectively preventing the depression of said spring means and allowing said spring means to act without restriction; resilient means about said shaft acting against said support housing and said armature biasing said shaft into said solenoid; and a shoulder provided in said support housing limiting the separation of said shaped upper portions of said arms and maintaining selected spaced relationship between said studs.

References Cited in the file of this patent UNITED STATES PATENTS 1,315,365 Hamm Sept. 9, 1919 1,880,122 Cooke Sept. 27, 1932 2,268,882 Lilja Jan. 6, 1942 2,341,457 Markey et al Feb. 8, 1944 2,430,617 Quinnell et al Nov. 11, 1947 2,720,835 Houston et a1. Oct. 18, 1955 FOREIGN PATENTS 328,662 Great Britain May 5, 1930 563,003 Great Britain July 25, 1944 

